Bacterial Growth Research Articles

Super protective effect, ultra-high juice absorption and long-term antibacterial of Ag-2MI@Chitosan biodegradable sponge for fruit preservation and transportation

Plastic foam packaging is often used for the transportation to avoid mechanical damage to the fruit, but it lacks antibacterial properties, water absorption and is non-degradable, leading to fruit decay and safety risks as well as serious environmental pollution. Herein, Ag-2-Methylimidazole@Chitosan (Ag-2MI@CS) was successfully synthesized by in situ synthesis at normal temperature and pressure, and improved the antibacterial performance of Ag-2MI@CS by using green solvent ethanol to adjust the solvent polarity. The results showed that the long-lasting inhibitory performance of Ag-2MI@CS was significantly improved, the long-lasting antibacterial time has been extended from 24 h to 96 h. Furthermore, Ag-2MI@CS can significantly protect fruits and reduce the damage of fruits, even when falling from a height of 60 cm or under extreme transportation conditions. Besides, Ag-2MI@CS had extremely high absorption rates of water and fruit juice, 1447.69 % and 1356.59 %, respectively, which was conducive to absorbing water generated by respiration and juice generated by damage during transportation, so as to avoid the growth of bacteria caused by water and fruit juice. Ag-2MI@CS can achieve fruit preservation in both indoor static and transportation dynamic conditions. This study offers novel insights into new biodegradable packaging material in fruit transportation.

Microbial Isolates and Antimicrobial Resistance Patterns in Adults with Inborn Errors of Immunity: A Retrospective Longitudinal Analysis of Sputum Cultures

Introduction: Individuals with inborn errors of immunity (IEI) are at increased risk of respiratory infection and frequently receive prolonged broad-spectrum antibiotics, leading to antibiotic resistance. The aim of this study was to identify respiratory pathogens and antibiotic resistance patterns in IEI patients. Methods: We retrospectively studied 36 IEI patients with positive bacterial growth in sputum cultures between 2014 and 2023. Data covered hospitalizations, respiratory infections, yearly antibiotic prescriptions, past sputum cultures, and antibiotic sensitivities. Patients with primary ciliary dyskinesia (PCD) and bronchiectasis served as a control group. Results: A total of 314 sputum cultures were analyzed from patients with IEI, alongside 585 cultures from individuals with PCD and 113 cultures from patients with bronchiectasis. Patients with IEI had a median age of 23.5 years, with 61% male participants. The study compared the differences in bacterial isolates from sputum cultures and antibiotic resistance between patients with IEI and the control groups. The most common bacterial isolates across all groups were Haemophilus influenzae (159 isolates in IEI vs. 314 in PCD and 26 in bronchiectasis), Pseudomonas aeruginosa, and Streptococcus pneumoniae. In IEI patients, 992 symptomatic respiratory exacerbations and 43 pneumonia-related hospitalizations were recorded. Notably, H. influenzae in IEI patients showed high resistance rates to cefuroxime (82%), amoxicillin/clavulanic acid (66%), trimethoprim/sulfamethoxazole (59%), and ampicillin/sulbactam (49%). P. aeruginosa in IEI patients displayed significant resistance to ciprofloxacin (85%), ceftazidime (42%), and aminoglycosides (23–33%). Additionally, all S. pneumoniae isolates in IEI patients were tetracycline resistant, with high resistance rates to penicillin, clindamycin, and erythromycin. It is essential to highlight the substantial resistance of common pathogens to oral antibiotics. In contrast, the control groups exhibited lower resistance rates across all bacterial isolates. Conclusion: Antimicrobial resistance is a growing concern among vulnerable IEI patients. We suggest conducting similar investigations in other regions to address this issue. The findings should inform future infection management guidelines for IEIs.

Microbial carbon utilization in a boreal lake under the combined pressures of brownification and eutrophication: insights from a field experiment

AbstractClimate and land use changes can increase terrestrial runoff to aquatic systems, leading to brownification and eutrophication in northern boreal lakes. Brownification may boost bacterial respiration and production, while eutrophication can enhance primary production and algal blooms. However, their combined effects on basal producers and bacterial carbon utilization are less understood. This study explores the combined impacts of the two stressors: brownification and eutrophication on microbial dynamics in Lake Bolmen. Utilizing a field mesocosm experimental design, treatments received different combinations of organic matter (OM) and inorganic nutrients to simulate predicted future scenarios. Results showed that OM additions significantly increased bacterial production and respiration, regardless of nutrient additions. Nutrient additions enhanced bacterial production but did not affect respiration. Both nutrients and OM stimulated bacterial growth efficiency. Labile carbon from DOM was the main driver of higher bacterial respiration and short-term production increases. Fluorescence data indicated that the combination of brownification and eutrophication led to higher terrestrial DOM utilization than each stressor alone. The study suggests that future boreal lakes may become more heterotrophic, thus increasing CO2 release. These findings highlight the complex interactions between DOM and nutrients and underscore the importance of considering multiple stressors in lake management and mitigation strategies.

The Influence of Exogenous CdS Nanoparticles on the Growth and Carbon Assimilation Efficiency of Escherichia coli.

This study investigated the impact of CdS nanoparticles (NPs) on Escherichia coli growth and metabolism under varying conditions. Under illumination, CdS NPs significantly enhanced bacterial growth, glucose assimilation, and biomass accumulation. Key metabolic and stress response genes showed increased expression, indicating improved ATP synthesis and oxidative stress resistance. Additionally, CdS NPs enhanced the electrochemical properties of E. coli, promoting efficient electron transfer. No significant changes were observed in the dark. These findings suggest that light-activated CdS NPs promote E. coli growth and metabolic efficiency by upregulating crucial genes involved in growth and oxidative stress management.

Anti-Bacterial Potential of Multi-strain Probiotics Lactiplantibacillus plantarum (Strain Dad-13 and FNCC-0250) and Lacticaseibacillus paracasei GMRMP-001 against Escherichia coli FNCC-0091 In Vitro and In Vivo

Lactiplantibacillus plantarum Dad-13, Lactiplantibacillus plantarum FNCC-0250 and Lacticaseibacillus paracasei GMRMP-001 are probiotics strain isolated from Indonesian local and traditional fermented foods. This study aims to evaluate the administration of multi-strain probiotics at dose of 109 CFU/mL/day for 14 days against the diarrhea-causing bacteria Escherichia coli FNCC-0091 at a dose of 1011 CFU/mL/day. Thirty rats were randomized and the divided into 5 groups, including control group, skim milk group, single-strain group, multi-strain group and E. coli group. Antibacterial activity was analyzed in vitro, feed intake, body weight were analyzed, microbial analysis was carried out on feces and cecum, short chain fatty acids were analyzed and intestinal morphology was measured. The result showed that the single-strain and multi-strain inhibition zone in in vitro test produces a very strong inhibitory potential (> 9 mm). The number of L. plantarum and L. paracasei increased and the number of E. coli decreased significantly in the feces and cecum of Rat indicating the survival rate of the probiotic bacteria in the digestive tract and their ability to fight pathogenic bacteria. The concentration of acetic acid, propionic acid and butyric acid compounds also increased, indicating that the digestive tract is at a low pH so that it can inhibit the growth of pathogenic bacteria in rats. In addition, consumption of multi-strain probiotics does not have a negative effect on intestinal morphology. The conclusion is that multi-strain probiotics are able to inhibit pathogenic bacteria in vivo and in vitro. HIGHLIGHTS Multi-strain probiotics isolated from traditional Indonesian fermented foods can reduce the potential for diarrhea. Single-strain and multi-strain have the same effectiveness in inhibiting pathogenic bacteria as seen from the growth of the bacteria. Digestive conditions were damaged in rat that were not given probiotic intervention, but when they received probiotic intervention, digestive conditions improved. GRAPHICAL ABSTRACT

Effect of Probiotic Supplementation in Diet on Egg Production, Egg Quality, Intestinal Morphology and Bacterial Population in Caecum of Laying Hens

The objective of this study was to study the effect of probiotic supplementation in diet on egg production, egg quality, intestinal morphology, and bacterial population in caecum of laying hens. A total of 768 Lohmann Brown-Classic laying hens, aged 42 - 54 weeks, were used. The laying hens were divided into 3 groups, each with 8 subgroups of 32 birds each. The experiment was planned to use a completely randomized design method. The 3 experimental groups were classified based on their dietary treatment as follows: 1) Basal diet (without probiotic supplementation), 2) Basal diet with probiotic 0.01 and 0.02 % in 3, respectively. Data was collected for 12 weeks. Adding probiotic in the diet was no significant difference on egg production, egg quality, and bacterial population in caecum. However, probiotic supplementation in the diet increased villi height of the duodenum significantly improved (p < 0.02), villi height per depth crypt of the duodenum significantly improved (p < 0.05), villi height per depth crypt of the jejunum significantly improved (p < 0.01), and villi height per depth crypt of the ileum significantly improved (p < 0.02). Therefore, studies have shown that dietary probiotic supplementation can improved small intestinal morphology are the most important indexes for measuring the digestive and absorption function of the small intestine are more efficient. HIGHLIGHTS Probiotic (Bacillus subtilis) is a gram-positive, non-pathogenic bacterium that can inhibit digestive enzymes such as protease, amylase, and lipase. These enzymes help increase the efficiency of digestion and absorption of nutrients. As a result of the working mechanism of Bacillus subtilis, it helps strengthen the intestinal wall, eliminates pathogenic microorganisms, reduces damaged intestinal mucosal cells, and improves intestinal absorption, resulting in increased production. Effect of probiotic (Bacillus subtilis) supplementation in laying hen diets on total bacterial load in appendix. No difference was found in the load of total bacteria and Escherichia coli (P > 0.05). Its beneficial properties stimulate the growth of beneficial bacteria in the intestines, such as Bifidobacteria sp. and Lactobacillus sp., causing the production of lactic acid, which makes the colon more acidic, resulting in inhibition of the growth of pathogenic microorganisms. GRAPHICAL ABSTRACT

Edwardsiella piscicida promotes mitophagy to escape autophagy-mediated antibacterial defense in teleost monocytes/macrophages

Edwardsiella piscicida is a Gram-negative intracellular pathogen. Currently, the immune evasion strategies of E. piscicida are not yet fully understood. In this study, we revealed that E. piscicida exploited mitophagy to enhance its intracellular survival in grass carp (Ctenopharyngodon idella) monocytes/macrophages. The results showed that in E. piscicida-infected cells, there was a significant loss of mitochondrial membrane potential and a marked increase in the production of mitochondrial reactive oxygen species (mtROS), indicating the damage to the mitochondria in the infected cells. Furthermore, fluorescence confocal images presented that E. piscicida infection elicited the colocalization of mitochondria with microtubule-associated protein 1 light chain 3 (LC3, a key marker molecule of autophagy) and lysosomes, suggesting the occurrence of mitophagy. This notion was supported by the findings that E. piscicida significantly stimulated LC3-II protein and damped Tom20 (a marker molecule of mitochondria) protein levels. Subsequently, a mitophagy inducer carbonyl cyanide m-chlorophenyl hydrazine (CCCP) and a mitophagy inhibitor mitochondrial division inhibitor 1 (Mdivi-1) were used to evaluate the role of mitophagy in modulating the intracellular survival of E. piscicida. The results revealed that CCCP significantly promoted intracellular survival of E. piscicida, whereas Mdivi-1 hindered the bacterial growth. Moreover, Mdivi-1 further increased the production of bacteria-induced mitochondrial ROS in an additive manner. In particular, CCCP suppressed and Mdivi-1 promoted the colocalization of LC3-II with E. piscicida, implying that E. piscicida-triggered mitophagy to facilitate its growth probably by subverting the autophagy targeting this bacterium, a previously known clearance pathway of E. piscicida. Overall, our findings suggest a new survival strategy employed by E. piscicida within fish monocytes/macrophages.

Development and Assessment of Herbal Sanitizer Derived from Plant Extract

Introduction: A key component in the prevention, management, and decline of healthcare-acquired illnesses is hand sanitizer. Multi-drug-resistant infections are among the persistent issues related to infections acquired while receiving medical care. Maintaining good hand hygiene can greatly lower the chance of cross-contamination. In recent times, hand sanitization has been increasingly popular as a means of reducing nosocomial infections that a variety of opportunistic bacteria can cause.  Method: Using a methanol solvent and a maceration method, the extract was obtained from the leaves of the neem and tulsi plants. The disc diffusion technique was used to determine and assess the antibacterial activity by measuring the diameter of the zone of inhibition. It was decided to create a herbal hand sanitizer.  Results: According to the study, both Ocimum sanctum and Azadirachta indica include terpenoids, alkaloids, glycosides, tannins, and saponins. All of the studied microorganisms displayed a zone of inhibition in the solvent extract within the 5-23 mm range. It was discovered that the extracts' antibacterial efficacy depended on concentration.  Conclusion: As a platform for further research and the creation of novel therapeutic entities, the study's findings indicate the presence of various phytochemical elements with antibacterial capabilities. We may infer that the stated organisms (S. aureus, K. pneumoniae, P. aeruginosa, & E. coli) are much less susceptible to bacterial growth when exposed to herbal sanitizer. Based on many anti-bacterial tests, it has been shown that the high-concentration formulation (40 mg/ml) is highly efficient in treating bacterial disorders.

Factors affecting the oral health of patients in intensive care units: a prospective observational study

Background: In the intensive care unit (ICU), oral flora changes and bacterial growth starts, negatively affecting oral health. Aims: This study aimed to evaluate the status of the oral mucus membranes of patients in ICUs and the factors affecting oral health. Methods: A descriptive and correlation design was used. The study included 151 patients in ICUs for five consecutive days. The assessments were performed using the Patient Form, Eilers Oral Health Assessment Scores and the Oral Health Assessment Chart. Results: Decayed teeth, magnesium levels and Glasgow coma scale were found to be effective in the first day oral health change of ICU patients and explained 22% of the oral health change, respectively. Age, decayed teeth, number of drugs used and Glasgow coma scale were found to be effective in the change in oral health of ICU patients on the fifth day and explained 35% of the change in oral health. Conclusions: Oral mucus membranes should be assessed closely and systematically in all critically ill patients who are of advanced age and are receiving a small number of medications, with a history of hyperglycaemia, high BUN, low albumin, hypocalcaemia, low Glasgow Coma Scale and decayed teeth.

Evaluating the Effects of Non-Nutritive Sweeteners on Pigs: A Systematic Review.

Non-nutritive sweeteners (NNS) have been investigated for their potential to improve feed palatability and growth performance in pigs, although their use in swine production remains limited. This systematic review evaluates the effects of NNS on pigs, drawing from 18 studies published between 1990 and 2024. Following the PRISMA guidelines and using the PICOS framework, a total of 448 papers were initially identified, of which 18 met the inclusion criteria for review. The results are mixed: some studies suggest that NNS like stevioside, sucralose, and neotame may improve performance and reduce diarrhea, while others show limited or no effects. The impact of NNS on gut microbiota is similarly inconsistent, with some sweeteners promoting beneficial bacterial growth, while others show minimal changes in microbial diversity. This review emphasizes the need for more research to clarify the effects of NNS in pigs, particularly the mechanisms behind their influence on growth and gut health. Additionally, further studies are needed to determine optimal dosages and assess the long-term impacts of NNS on pig immune function and overall health. The findings highlight the current gaps in knowledge and suggest that more evidence is needed to understand the role of NNS in swine nutrition.

Comparison and mechanism study on solidification of loose pisha sandstone by indigenous bacteria and sporosarcina pasteurii

Pisha sandstone is a kind of sandstone which is easy to collapse by water in Shanxi, Shaanxi and Inner Mongolia of China, and suffers from hydraulic erosion all the year round. In recent years, some scholars have used microbial induced calcium carbonate precipitation (MICP) technology to solidify Pisha sandstone to improve the water erosion resistance of Pisha sandstone. However, for the climate environment with low average temperature in Pisha sandstone area, the commonly used Sporosarcina pasteurii are not well adapted. The purpose of this study is to use the indigenous strainsto solidify the loose Pisha sandstone, and to compare the growth adaptability, mechanical properties and water erosion resistance of the solidified layer with Sarcina pasteurii at different temperatures, and to explore the mechanism of different temperatures and strains affecting the microbial solidification of Pisha sandstone from the micro scale. At the same time, a mixed bacterial liquid solidification test was also set up. The results showed that the solidified thickness of indigenous strains was 4.65 % higher than that of Sporosarcina pasteurii, and the thickness and strength of mixed strains were increased by 19.57 % and 36.62 %, respectively. The growth and solidification effect of indigenous strains were less affected by low temperature. Compared with Sporosarcina pasteurii, at low temperature, the bacterial concentration decrease of indigenous strains was reduced by 26.13 %, the thickness loss of solidified layer was reduced by 13.04 %, and the strength loss of solidified layer was reduced by 13.39 %. The effect of low temperature on the growth of bacteria is mainly reflected in affecting the maximum concentration of bacteria and the growth rate. The effect on MICP mainly reflected in affecting the life activities of bacteria and the crystal form and morphology of calcium carbonate. The research results provide a theoretical basis for the MICP technology application of indigenous strains and multi-strains in Pisha sandstone area soil reinforcement and solidification slope.

Unveiling the Potential of Protein-Based Sustainable Antibacterial Materials.

The surge in bacterial growth and the escalating resistance against a multitude of antibiotic drugs have burgeoned into an alarming global threat, necessitating urgent and innovative interventions. In response to this peril, scientists have embarked on the development of advanced biocompatible antibacterial materials, aiming to counteract not only bacterial infections but also the pervasive issue of food spoilage resulting from microbial proliferation. Protein-based biopolymers and their meticulously engineered composites are at the forefront of this endeavor. Their potential in combating this severe global concern presents an approach that intersects the domains of biomedicine and environmental science. The present review article delves into the intricate extraction processes employed to derive various proteins from their natural sources, unraveling the complex biochemical pathways that underpin their antibacterial properties. Expanding on the foundational knowledge, the review also provides a comprehensive synthesis of functionalized proteins modified to enhance their antibacterial efficacy, unveiling a realm of possibilities for tailoring solutions to specific biomedical and environmental applications. The present review navigates through their antibacterial applications; from wound dressings to packaging materials with inherent antibacterial properties, the potential applications underscore the versatility and adaptability of these materials. Moreover, this comprehensive review serves as a valuable roadmap, guiding future research endeavors in reshaping the landscape of natural antibacterial materials on a global scale.

Challenges in diagnosing bovine tuberculosis through surveillance and characterization of Mycobacterium species in slaughtered cattle in Kolkata

BackgroundTuberculosis in cattle is caused by Mycobacterium tuberculosis complex (MTBC) species. Apart from MTBC, different Nontuberculous Mycobacteria (NTM) species have also been isolated from cattle. The presence of NTM infection in bovines makes the diagnosis of bovine tuberculosis (bTB) a cumbersome task. Therefore, a cross sectional study was conducted to isolate and characterize different Mycobacterium spp. from a slaughterhouse situated in Kolkata, a city in the eastern part of India.ResultsOut of 258 morbid samples, 98 isolates were found to be positive for bacterial growth, and 35% (n = 34) were positive for Mycobacterium. 94% of Mycobacterial cultural isolates were NTM (n = 32), and the rest (n = 2) were found to be MTBC. Species-level identification of the isolates by hsp65 sequencing revealed that out of 32 isolates, 24 were M. fortuitum, three were M. abscessus, two each were M. chelonae and M. parascrofulaceum, and one was M. novocastrense. A phylogenetic tree with partial hsp65 gene sequences was also constructed to determine the relatedness of the unknown isolates to the reference strains.ConclusionBoth NTM species and MTBCs were identified from TB-like lesions in cattle that were slaughtered at the Kolkata abattoir. This discovery may indicate that NTM contributes to the development of lesions in cattle. Also, we recommend implication of more specific diagnostic tests for bTB.

Virtual Screening Uncovers DspS Activators That Disperse Pseudomonas aeruginosa Biofilms.

Pseudomonas aeruginosa is the predominant bacterium found in many chronic biofilm infections. Over the past few decades, biofilm-related infections have posed a significant challenge to medical practice due to the increasing emergence of multidrug resistance. Cis-2-decenoic acid (CDA), a small molecule found in P. aeruginosa, has been shown to disperse biofilms formed by various bacteria and to work in synergy with common antibiotics. Despite that, the binding mechanism between CDA and the predicted cyclases/histidine kinases associated sensory extracellular (CHASE) domain of sensor protein DspS remains unknown in the absence of a crystallized protein structure. Moreover, the therapeutic potential of CDA is limited by its susceptibility to oxidative degradation and isomerization. In this work, we propose a structural model for the DspS CHASE domain. The resulting model displays an overall topology reminiscent of the sensor protein PcrK in Xanthomonas campestris. Through molecular dynamics simulations, a stable potential binding site for CDA was further identified. Virtual screening against the predicted site of DspS CHASE using our developed pipeline discovered two promising compounds, compounds 2 and 9, capable of dislodging 7-day P. aeruginosa biofilms at 50 μM without affecting bacterial growth. These compounds also enhanced the effects of ciprofloxacin against P. aeruginosa, reduced the survival of dispersed cells, and increased the expression of matrix-degrading enzyme genes pelA, pslG, and eddA. This study provides insights into CDA recognition by DspS and represents the first large-scale effort to uncover first-in-class DspS activators. At the same time, this work also underscores the effectiveness of a computational-aided drug discovery process in finding new activators, even without a known protein structure.

Physiological characteristics of microbial transformation during chronic exposure to triclosan as a hydrophobic antibacterial agent and post-antibacterial cessation

ABSTRACT The use of triclosan (TCS) in hygiene products and other materials raises concerns about increased antimicrobial resistance. Research has shown that bacteria can develop resistance to TCS, but there is limited understanding of how bacterial behavior changes after TCS is removed. This study focuses on how bacteria adapt to prolonged TCS exposure and recover after its removal. It aims to improve practices for using antimicrobial agents in sanitation products and emphasize the importance of understanding exposure and recovery times to prevent resistance development. The study evaluated the bacterial behavior, determining the minimum inhibition concentration of TCS that 90% of Escherichia coli was inhibited (MIC90), predicting bacterial growth kinetics using the Modified Gompertz model and membrane permeability recovery. Bacteria showed a significant increase in resistance levels during exposure, with the MIC90 steadily increasing over 30 days and peaking at 16 mg/L. Upon removal, there was a notable 2-fold decrease in resistance after 10 days of reculturing in a non-chemical medium, likely due to restructuring changes in cell membranes. Therefore, in addition to reducing the occurrence of antibacterial agents in the environment, advanced treatments for eliminating antibacterial resistance should be performed on wastewater before being discharged into the environment.

Impact of Nutrient Starvation on Biofilm Formation in Pseudomonas aeruginosa: An Analysis of Growth, Adhesion, and Spatial Distribution.

Objectives: This study investigates the impact of nutrient availability on the growth, adhesion, and biofilm formation of Pseudomonas aeruginosa ATCC 27853 under static conditions. Methods: Bacterial behaviour was evaluated in nutrient-rich Luria-Bertani (LB) broth and nutrient-limited M9 media, specifically lacking carbon (M9-C), nitrogen (M9-N), or phosphorus (M9-P). Bacterial adhesion was analysed microscopically during the transition from reversible to irreversible attachment (up to 120 min) and during biofilm production/maturation stages (up to 72 h). Results: Results demonstrated that LB and M9 media supported bacterial growth, whereas nutrient-starved conditions halted growth, with M9-C and M9-N inducing stationary phases and M9-P leading to cell death. Fractal analysis was employed to characterise the spatial distribution and complexity of bacterial adhesion patterns, revealing that nutrient-limited conditions affected both adhesion density and biofilm architecture, particularly in M9-C. In addition, live/dead staining confirmed a higher proportion of dead cells in M9-P over time (at 48 and 72 h). Conclusions: This study highlights how nutrient starvation influences biofilm formation and bacterial dispersion, offering insights into the survival strategies of P. aeruginosa in resource-limited environments. These findings should contribute to a better understanding of biofilm dynamics, with implications for managing biofilm-related infections and industrial biofouling.

Role of Denitrification in Selenite Reduction by Azospirillum brasilense with the Formation of Selenium Nanoparticles.

Many bacteria are capable of reducing selenium oxyanions, primarily selenite (SeO32-), in most cases forming selenium(0) nanostructures. The mechanisms of these transformations may vary for different bacterial species and have so far not yet been clarified in detail. Bacteria of the genus Azospirillum, including ubiquitous phytostimulating rhizobacteria, are widely studied and have potential for agricultural biotechnology and bioremediation of excessively seleniferous soils, as they are able to reduce selenite ions. Cultures of A.brasilense Sp7 and its derivatives (mutant strains) were grown on the modified liquid malate salt medium in the presence or absence of selenite. The following methods were used: spectrophotometric monitoring of bacterial growth; inhibition of glutathione (GSH) synthesis in bacteria by L-buthionine-sulfoximine (BSO); optical selenite and nitrite reduction assays; transmission electron microscopy of cells grown with and without BSO and/or selenite. In a set of separate comparative studies of nitrite and selenite reduction by the wild-type strain A.brasilense Sp7 and its three specially selected derivatives (mutant strains) with different rates of nitrite reduction, a direct correlation was found between their nitrite and selenite reduction rates for all the strains used in the study. Moreover, for BSO it has been shown that its presence does not block selenite reduction in A.brasilense Sp7. Evidence has been presented for the first time for bacteria of the genus Azospirillum that the denitrification pathway known to be inherent in these bacteria, including nitrite reductase, is likely to be involved in selenite reduction. The results using BSO also imply that detoxification of selenite through the GSH redox system (which is commonly considered as the primary mechanism of selenite reduction in many bacteria) does not play a significant role in A.brasilense. The acquired knowledge on the mechanisms underlying biogenic transformations of inorganic selenium in A.brasilense is a step forward both in understanding the biogeochemical selenium cycle and to a variety of potential nano- and biotechnological applications.

Bacterial contamination of platelets concentrates in a lower middle-income country: Data from a single tertiary care hospital

BackgroundTransfusion of bacterially contaminated platelets may cause life threatening sepsis in the recipients. Cost of platelet screening is a major challenge for low middle income countries (LMICs). In this study, we evaluated the frequency of bacterial contamination in the platelet units (PUs) and the outcome of transfusing such platelets to the patients in a single institute at Pakistan. Material and methodsDuring 2018–2022, whole blood-derived (WB-PU) and apheresis platelets (AP) were screened by BacT-ALERT® automated system. Single sample from each AP and samples from ≤ 5 WB-PUs were pooled and cultured within 24 h-post collection. An initial positive signal was followed by re-culture, Gram’s staining, pool resolution and bacterial identification. Results were interpreted as ‘confirmed positive’ or ‘indeterminate’ and ‘confirmed negative’ based on differences in initial-reactive and final results. ResultsA total of 84246 PUs (476 AP and 83770 WB-PU) was screened, and 239 (0.28 %) culture bottles were positive on day one. Individual cultures were performed on 1378 PUs (239 bottles) for pool resolution. Seven of 1378 (0.5 %) PUs were ‘confirmed positive’ while 1371 (99.4 %) were ‘indeterminate’. No bacterial growth was observed in 82868 (82392 WB-PU and 476 AP) of 84246 (98.3 %). Overall bacterial contamination rate was low at 1 in 12000 PUs approximately. Seven patients were transfused with contaminated PUs but no transfusion reaction was observed. ConclusionAn insignificant risk of bacterial contamination was observed in this study but remains a concern for patient safety. LMICs need cost effective but efficient techniques to screen platelets for the presence of bacteria.

Impact of Nanoparticle Addition and Ozone Pre-Treatment on Mesophilic Methanogenesis in Temperature-Phased Anaerobic Digestion

Biodegradable organic waste offers significant opportunities for resource recovery within the frame of the circular economy. In this work, the effects of carbon-encapsulated iron nanoparticles and ozone pre-treatments in the mesophilic methanogenic stage of a temperature-phased an-aerobic digestion have been studied using biochemical methanogenic potential (BMP) tests and modeling simulation. To do that, digestates from a pre-treated thermophilic acidogenic reactor that co-digested sludge and wine vinasse were used. The addition of nanoparticles favored the removal of particulate matter, which increased by 9% and 6% in terms of total solids and volatile solids, respectively. When combined with ozone pre-treatment, these increases were 27% and 24%, respectively, demonstrating enhanced AD efficiency. The dose of iron nanoparticles encapsulated in carbon did not result in a statistically significant increase in methane production when sludge and vinasse were used as feedstock. The combination of nanoparticles with the ozone pre-treatment significantly improved the methanogenic phase of the second stage, increasing the methane production yield by 22% and reducing the lag phase from 10 days to 3 days, according to the modified Gompertz model.

Characterization of antibiotic resistance development of E. coli in synthetic and real wastewater.

Antimicrobial resistance (AMR) ranks among the leading global threats to public health and development. In 2019, bacterial AMR was estimated to have directly caused 1.27 million deaths worldwide and contributed to 4.95 million deaths overall (Murray, C. J., et al., (2022). Global burden of bacterial antimicrobial resistance in 2019: a systematic analysis. The Lancet, 399 (10325), 629-655.). With estimations of AMR only getting worse, it is imperative that we understand the complex dimensionalities that drive the genesis of antimicrobial resistance to where it begins-the environment. The paper investigates bacterial growth and AMR in real wastewater samples and highlights the importance of using a media that closely mimics real wastewater in AMR studies, compared to standard lab media like LB broth. This is crucial for understanding how E. coli and other bacteria develop AMR in environments similar to actual wastewater, which can inform more effective strategies to combat AMR in natural and engineered settings.